1. Field of the Invention
The invention is a device for transfer from a gaseous to a liquid phase. The gaseous phase dissolves in the liquid phase and subsequently reacts in the liquid phase.
This device is designed mainly to carry out treatments such as chemical, biological and metabolic reactions that include the transfer from a gaseous phase to a liquid phase. The liquid phase can be industrial or potable water.
Many treatments make use of chemical or biological transformations which require the inclusion, in the reaction medium of a gaseous composition needed for the chemical, biochemical and metabolic reactions of the microorganisms present in the reaction medium that the liquid phase represents. The device of the invention is particularly useful for aerobic treatment of water. To be effective, the systems require intimate mixing of the two phases.
2. Related Art
There are known devices such as surface aerators having stationary or floating turbines, which may run slow or fast, or use brushes, immersed systems which require injection of air such as static ventilators, vibrator valves and porous atomisers and the circulating systems using self-priming pumps with stationary or mobile jets.
The known devices provide homogeneous mixtures at the expense of a high consumption of energy.
There are known devices that use a venturi ejector to ensure the aeration of the liquid phase. They are more economical in energy consumption than the devices cited above.
The intrinsic performances of aeration equipment can be appraised through two criteria, namely:
1) The specific utilization of kilograms of oxygen per kilowatt-hour; and
2) The transfer coefficient in seconds .sup.-1.
The transfer coefficient by definition relates to the rate of variation of concentration to the difference between the concentration and the concentration corresponding to that of saturation of the gaseous phase in the liquid phase. The apparatus customarily used has raw specific utilization generally between 0.8 and 1.8 kilograms of oxygen per kilowatt-hour.
A study made by WANG, et al in 1978, and published in Chem. Eng. Sci., 33,945 in 1978, showed that coefficients of transfer as high as 0.22 second .sup.-1 could be obtained by using bubble columns equipped with static mixers for velocities of liquid and of gas respectively equal to 0.17 meter per second and 0.25 meter per second. The most popular devices which are the classical venturi or the porous atomiser, make it possible to obtain transfer coefficients between about 0.06 and 0.13 second .sup.-1.